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Biomedical subjects

D K James

Publications and source records attributed to D K James.

At least 37 records · Page 2Linked to original sources
PubMed1997

Antenatal genetic counselling: implications for population screening.

Only 1-2% of newborns have a congenital abnormality, yet it is responsible for the much greater proportion of mortality and morbidity in infancy and in childhood as well as during pregnancy. Because of this prevalence, there have been many developments in screening and diagnosis of congenital abnormality. Yet there are a number of limitations about how the screening and diagnostic service is currently operated. These limitations centre on the information that is provided, who undertakes the counselling, and their training and support provided to parents in making important decisions.

Congenital Abnormalities↗
PubMed1996

The potential impact of PR interval analysis of the fetal electrocardiogram (FECG) on intrapartum fetal monitoring.

A retrospective study was performed at the Queens Medical Centre, Nottingham, UK to evaluate the potential value of PR interval analysis of the FECG compared to conventional intrapartum assessment with fetal heart rate monitoring. Two-hundred sixty-five labours were selected for monitoring. Outcome was assessed by the number of fetal scalp blood samples (FBS) performed and the associated incidence of acidosis in the first stage of labour, the mode of delivery and whether or not this was expedited for fetal heart abnormality or an abnormal scalp pH. The condition of the fetus at delivery was assessed by arterial and venous blood acid-base status, Apgar score and the need for admission to the neonatal intensive care unit. Conventional electronic fetal heart rate monitoring (EFM) was used in all labours. The addition of PR interval assessment would potentially reduce the numbers of normal FBSs being carried out from 85.5% to 26.8% and the proportion of cases of missed acidosis at delivery from 8.5% to 4.5%. These results highlight the potential benefit of PR interval analysis in improving interpretation of the intrapartum cardiotocograph and need to be tested by prospective randomised controlled study.

Electrocardiography↗
PubMed1996

Improved intrapartum surveillance with PR interval analysis of the fetal electrocardiogram: a randomized trial showing a reduction in fetal blood sampling.

OBJECTIVE: Our goal was to test the hypothesis that the addition of fetal electrocardiogram time-interval analysis to conventional electronic fetal monitoring would significantly reduce the number of cases requiring fetal scalp blood sampling without an increase in adverse outcome. STUDY DESIGN: A randomized prospective trial was performed in 214 women with high-risk labor. RESULTS: There was a significant reduction in the number of cases that had fetal blood sampling performed in the fetal electrocardiogram plus electronic fetal monitoring group (risk ratio for electronic fetal monitoring alone 3.53; p < 0.01, 95% confidence interval 1.39 to 8.95). The fetal blood samplings performed in the electronic fetal monitoring alone group were less likely to be abnormal (pH < 7.25, base excess < -8.0) than those performed in the fetal electrocardiogram plus electronic fetal monitoring group (risk ratio for electronic fetal monitoring alone 0.62, p = 0.05, 95% confidence interval 0.35 to 1.10). There was a trend of more infants with an arterial umbilical pH < 7.15 and a base excess less than -8.0 mmol/L at birth being unsuspected and more instrumental deliveries for presumed fetal distress being performed in the electronic fetal monitoring alone than in the fetal electrocardiogram plus electronic fetal monitoring group. CONCLUSION: The addition of fetal electrocardiogram analysis to conventional electronic fetal monitoring during labor can reduce significantly the number of parturients undergoing fetal scalp blood sampling and can simultaneously increase its efficiency without an increase in adverse outcome.

Acidosis↗
PubMed1996

The fetal electrocardiogram.

Advances in microprocessing technology have made fetal ECG analysis a feasible adjunct to fetal surveillance. Time interval and morphology changes of the FECG occur during fetal hypoxia. The use of these changes to detect a fetus at risk of intrapartum asphyxia awaits validation in terms of both future and ongoing clinical trials. Recognition of FECG changes during decelerations may improve the sensitivity of EFM. Antepartum FECG analysis has potential for the detection of a number of pathological fetal conditions, including intrauterine growth retardation, but remains hampered by low signal-to-noise ratios, rendering successful signal acquisition unreliable.

Disease Models, Animal↗
PubMed1996

Changes in the PR interval--fetal heart rate relationship of the electrocardiogram during fetal compromise in chronically instrumented sheep.

OBJECTIVES: The evaluation of the changes in the relationship of the PR interval and fetal heart rate during prolonged fetal compromise in sheep at levels of acidosis comparable to those seen during human fetal compromise and to see whether these changes are potentially of use in the detection of fetal distress. STUDY DESIGN: A retrospective analysis of continuous fetal electrocardiogram recordings during graded fetal hypoxemia in 20 chronically cannulated fetal sheep was performed. Baseline recordings during normoxemia were compared with recordings during hypoxemia by use of Fisher's exact test and the Student t test. RESULTS: Sixteen of the 20 cases could be used for final analysis. Twelve showed a statistically significant change from a predominantly negative relationship between the PR interval and the fetal heart rate during normoxemia to a predominantly positive relationship during hypoxemia. Two cases showed an obvious trend in the same direction, which was statistically not significant. In two other cases no change in the relationship was observed. CONCLUSION: A changing relation between the PR interval and the fetal heart rate is of potential use in the detection of fetal compromise.

Animals↗
PubMed1995

Computerised fetal heart rate analysis in labour--effect of sampling rate.

OBJECTIVE: To study the effect of sampling rate on the accuracy of fetal heart rate recording in labour. DESIGN: Prospective observational study. METHODS AND SUBJECTS: The fetal heart rate was obtained from 153 fetuses in labour. The heart rate data was sampled at a rate of 0.5 Hz (every 2 s) and the means and standard deviations of 5-min segments compared against the mean and standard deviation for all beats in the same time interval. RESULTS: There was a highly significant correlation between the means (r = 0.994, p < 0.001) and standard deviations (r = 0.957, p < 0.001) of FHR sampled on successive beats compared with 2 s sampling. CONCLUSION: Two second sampling of the fetal heart rate in labour will allow a highly complex analytical algorithm to process the signal in near real time for objective analysis.

Algorithms↗
PubMed1995

Atrioventricular block during fetal heart rate decelerations.

Electrocardiograms (ECG) was examined in 15 fetuses during fetal heart rate decelerations in labour. Sinus bradycardia was demonstrated in six cases and in two cases inversion of the P wave was seen. In seven cases there was complete dissociation of the P wave from the QRS complex, indicating complete atrioventricular heart block. Many decelerations are vagally mediated, but such cases associated with complete atrioventricular heart block may be due to the effect of hypoxia on the bundle of His.

Bradycardia↗
PubMed1994

Cumulative changes in the fetal electrocardiogram and biochemical indices of fetal hypoxia.

Previous studies have shown that the relationship between P-R interval of the fetal electrocardiogram (FECG) and the fetal heart rate (FHR) varies according to the acid-base status of the fetus. In the normal fetus there is a negative correlation between these two parameters. However, as acidosis develops, the relationship becomes positive. In order to express this relationship in a quantitative form, an index known as the ratio index (RI) has been derived. This index provides a cumulative time based description of the relationship between the P-R interval and FHR for the whole labour. The aim of this study was to evaluate this derived index and compare it with fetal hypoxia. The FECG was recorded from 132 fetuses during labour using a fetal scalp electrode, and analysed using the Nottingham FECG system. Changes in the nature of this relationship between the P-R interval and heart rate were compared against biochemical markers of asphyxia, namely umbilical artery pH, lactate and umbilical venous norepinephrine and hypoxanthine. Significant correlations were demonstrated between the RI and umbilical arterial pH (r = -0.38, P < 0.01), lactate (r = 0.36, P < 0.01), log10norepinephrine (r = 0.37, P < 0.01), and hypoxanthine (r = 0.28, P < 0.01). The measurement of the ratio index during labour may be a useful method of determining fetal hypoxia during labour.

Electrocardiography↗
PubMed1993

Amniotic fluid zinc and pregnancy outcome.

OBJECTIVE: To examine for an association between amniotic fluid zinc and pregnancy outcome. DESIGN: A prospective study. SETTING: Southmead Hospital, Bristol, UK. SUBJECTS: 191 amniotic fluid samples from 11 centers in the Southwest of England, obtained at 16-20 weeks gestation. METHOD: Samples of amniotic fluid (AF) sent for prenatal diagnosis were collected from the laboratory and analysed for zinc level. Data were then collected at a later date concerning pregnancy outcome. OUTCOME MEASURE: Antenatal complications as well as events in labour, and in particular birth weight and congenital malformations. RESULTS: 182 cases with complete data showed a mean AF zinc level (+/- S.E.) of 1.39 (+/- 0.11). There was no relation between AF zinc and antepartum haemorrhage, pregnancy-induced hypertension, post-partum haemorrhage or time and mode of delivery. Neither was there an association with birth weight. As there were no cases with major malformations, particularly of the central nervous system, possible association could not be ascertained. CONCLUSION: The study failed to demonstrate any association between AF zinc and abnormal pregnancy outcome. A modified prospective study is suggested to explore this further.

Adult↗
PubMed1993

Reagent strip testing of antenatal urine specimens for infection.

OBJECTIVE: To compare reagent strip testing (RST) with microscopy and culture in identifying significant bacteriuria, and secondly, to consider potential cost savings if RST screening proved to be reliable. DESIGN: Prospective descriptive study. SETTING: Antenatal Clinic, Bristol Maternity Hospital. SUBJECTS: Eight hundred and ninety-eight women having urine testing in pregnancy for microscopy and culture either routinely or because of a clinical infection. INTERVENTIONS: The midstream specimens of urine had RST examination using Ames Multistix 8SG prior to being sent to the laboratory. MAIN OUTCOME MEASURE: Significant culture (> 10(5) colonies/ml) of a single organism in culture. RESULTS: The highest predictive value for a negative result of the urine culture (99.7%) was obtained when using four RSTs in combination. The RST for nitrite had a high predictive value for a positive urine culture (90%). The samples which gave a false negative result with RST screening were mainly infected with low grade urinary pathogens or genital tract contaminants. CONCLUSION: RST screening for bacteriuria provides a reliable and cheap alternative to culture of all urine specimens.

Bacteriuria↗
PubMed1992

Comprehensive fetal assessment with three ultrasonographic characteristics.

OBJECTIVES: When three ultrasonographic characteristics--umbilical artery Doppler recording, growth (abdominal circumference), and biophysical profile score--are used in combination in assessment of fetuses at risk of chronic asphyxia: (1) What are the order and time scale for the development of abnormality with each characteristic? (2) What is the short-term outcome associated with abnormalities of the three characteristics? (3) Should we amend our fetal assessment protocol? STUDY DESIGN: An audit of 103 fetuses (100 mothers) referred to a tertiary center for fetal assessment because of suspected chronic fetal asphyxia was performed with three ultrasonographic characteristics, umbilical artery Doppler recording, measurement of abdominal circumference, and documenting the biophysical profile score. RESULTS: The order of deterioration (which had a very variable time scale) was umbilical artery Doppler recording, followed by abdominal circumference and finally biophysical profile score. Normal characteristics or an abnormal umbilical artery Doppler recording alone or an abnormal abdominal circumference alone was associated with an excellent prognosis. The worst outcome was found in the 28 fetuses with abnormality of all three ultrasonographic features before delivery. CONCLUSIONS: The main suggested implications for management are avoidance of preterm delivery with normal ultrasonographic characteristics, an abnormal umbilical artery Doppler recording alone, or an abnormal abdominal circumference alone; delivery of fetuses at greater than or equal to 34 weeks with abnormal umbilical artery Doppler recording and abdominal circumference before the biophysical profile score becomes abnormal; and implementation of specific measures to prevent necrotizing enterocolitis in newborns when all three characteristics are abnormal.

Abdomen↗
PubMed1992

The development of ultradian rhythms in the human fetus.

OBJECTIVE: Our objective was to determine the normal sequence of neurobehavioral development in the human fetus between 14 weeks' gestation and delivery. STUDY DESIGN: The study was performed by longitudinal ultrasonographic observation of 45 low-risk singleton fetuses. RESULTS: During the first half of the midtrimester there was a high rate of spontaneous movement that appeared randomly distributed. By the end of that trimester an increase in the duration of intervals of quiescence resulted in activity appearing cyclically distributed, with the duration of quiet cycles progressively increasing to term. Fetal mouthing and breathing were linked with cyclic behavior from the time of their emergence. Fetal heart rate pattern A could be recognized from around 32 weeks, due to a reduction in baseline variability in quiet cycles after 30 weeks, whereas pattern B could be recognized several weeks earlier. From the time cyclic behavior and heart rate patterns could be recognized, intervals of coincidence of the fetal behavioral state variables increased progressively with advancing gestation.

Activity Cycles↗
PubMed1992

Management of severe pre-eclampsia and eclampsia by UK consultants.

OBJECTIVE: To determine the current management of severe pre-eclampsia and eclampsia in the United Kingdom. DESIGN: One-page postal survey to all (1007) UK consultant obstetricians with questions about use of antihypertensive and anticonvulsant drugs in severe pre-eclampsia and eclampsia, other management strategies, definition of factors determining severity, protocol development and regional review. RESULTS: 688 replies (69.6% response rate). The antihypertensive drugs used were mainly oral labetalol (35%), oral methyl dopa (23%) and parenteral hydralazine (29%); diuretics were not used. Diazepam was the preferred drug in eclampsia. Very few consultants used magnesium sulphate (2%). Anticonvulsants were also prescribed by 85% of consultants to prevent fits; the drugs then preferred were diazepam (41%), phenytoin (30%) and chlormethiazole (24%). Two-thirds of consultants felt there was a need for trials to study the effectiveness of antihypertensive and anticonvulsant drugs. In a woman with proteinuric hypertension, 15% of consultants did not regard the development of headache as indicating severe pre-eclampsia. Consistent management practices were not associated with agreement about protocols. Regional review does not appear to have occurred. CONCLUSION: Antihypertensive and anticonvulsant therapies are widely used but trials are considered necessary. Improvements in the management of women with severe pre-eclampsia or eclampsia might occur if UK obstetricians sought more collective opinion and undertook regional audit of protocols.

Anticonvulsants↗
PubMed1992

Pre-eclampsia and trisomy 13.

OBJECTIVE: To assess the reported association between field trisomy 13 and maternal pre-eclampsia. DESIGN: A retrospective case-control study. SUBJECTS: Twenty-five women who gave birth to trisomy 13 infants in southwest England between 1971 and 1989; 38 women who gave birth to trisomy 18 infants in the same region over the same time and 50 women with normal karyotype infants matched for age, parity, and date of delivery with the trisomy 13 group. MAIN OUTCOME MEASURES: The medical records of all the women in the three groups were analysed for evidence of pre-eclampsia. Four different thresholds of pre-eclampsia were used. The incidence of pre-eclampsia was compared between the three study groups and analysed separately for primigravid and multigravid women. RESULTS: The incidence of pre-eclampsia in pregnancies complicated by trisomy 13 was significantly higher than the incidence in the trisomy 18 and the normal karyotype control groups. This association was more pronounced in primigravid pregnancies. CONCLUSIONS: This, the largest survey of trisomy 13 and pre-eclampsia to date, suggests an association between the two conditions. It also supports the argument for a fetal factor in the pathogenesis of pre-eclampsia. We speculate on how genes encoded on chromosome 13 may be responsible.

Case-Control Studies↗